Argthtjtr

this is the json received as parameters from external angular webapp:

{

  "provincia": {

    "id": 1,

    "name": "Province"

  },

  "username": "tester",

  "direccion": "new avenue 100",

  "email": "nomail@mail.com"

}

this is my controller

 def create

   @seller = Seller.new(seller_params)



  if @seller.save

    render json: @seller, status: :created, location: @seller

  else

    puts @seller.errors.full_messages

    render json: @seller.errors, status: :unprocessable_entity

  end

end

this is seller_params

def seller_params

    params.require(:seller).permit(:username, :direccion, :email, :provincia_id)

end

models: Seller belongs_to Provincia

server console output error full message

Provincia must exist

Which modification in the Rails API should I do to make it work, and save the new seller? thanks in advance.

The way that you are permiting your params in the controller are not correct:

Rails Docs

You need to pass your provincia_id in your attributes or permit that params that are you passing by

Way 1:

{

  "provincia_attributes": {

    "id": 1,

    "name": "Province"

  },

  "username": "tester",

  "direccion": "new avenue 100",

  "email": "nomail@mail.com"

}

SellersController.rb

def seller_params

  params.require(:seller).permit(:username, :direccion, :email, provincia_attributes: [:id, :name])

end

Way 2

{

  "provincia_id": "1"

  "username": "tester",

  "direccion": "new avenue 100",

  "email": "nomail@mail.com"

}

SellersController.rb

def seller_params

  params.require(:seller).permit(:username, :direccion, :email, :provincia_id)

end

Try changing the params like this:

def seller_params

  p = params.require(:seller).premit(:username, :direccion, :email).to_h

  p[:seller][:provincia_id] = params[:seller][:provincia][:id]

  p

end

That will add the "provincia_id" key you are missing for the association. I call to_h to get a new hash because I don't like to mutate the original params and you have already permited the values you want so that Hash is safe to use.